1. Technical Field
The invention relates to a card wire. The new card wire can e.g. be used on cylinders on revolving flat cards. Other applications include lickerin rollers on roller cards and on revolving flat cards as well as cylinders on roller cards. The invention describes a method to make such card wires as well.
2. Background Art
In issue No. 25 (August 2011) of the magazine “Spinnovation”, a “camel type” card wire is proposed for use on cylinder and lickerin rollers of revolving flat cards. The tooth has a tip which has the traditional shape, and in addition to it one hump at the back of the tooth at a distance from the tip of the tooth and positioned considerably lower than the tip of the tooth. Such a wire is shown in FIG. 1. The claimed benefit of the camel shape is a positive effect on the airflow on the clothing surface. And as a result, the fibres are kept on the surface of the cylinder wire much better, thus preventing the fibres from sliding into the clothing. The closer positioning of the fibres to the revolving flats is said to enhance the carding process. After re-sharpening the tips of the “camel type” wire, the fibres will even be closer positioned to the revolving flats, further enhancing the carding process. The doffer on the card is said to take more fibres when using the “camel type” cylinder wire. Using the “camel type” wire on lickerin rollers is claimed to result in the improvement of fibre transfer between lickerin and cylinder as well as to increase extraction of trash, as trash and fibres are kept on the surface of the lickerin wire.
CN201258379Y describes a card wire with a traditional tip of the tooth. The wire is characterized in that it has a horizontal platform (meaning a platform parallel with the direction of the card wire) on the back of each tooth of the toothed part. The platform is positioned at a distance below the tip of the tooth. A transition zone is present between the tip of the tooth and the platform. An arc-shaped transition is provided between the platform and the bottom of the tooth. Due to the platform on the back of the tooth, the strength of the tooth tip is increased. Additionally, the platform can prevent fibres from sinking to the tooth bottom. By appropriately increasing the tooth pitch to increase the fibre-holding capacity, the tooth tip strength and the transfer capability are increased, thereby improving the carding effect and improving the yarn quality.
It is general practice to re-sharpen cylinder wires on revolving flat cards a number of times over their useful life. Re-sharpening restores the tooth to sharp leading edges, removing the rounding at the tip. However the creation of a flat surface at the tip of the wire cannot be avoided. This flat surface means that the tooth has lost sharpness compared to its initial state and hence that carding performance is reduced in that fibres can less easily be taken (e.g. from the revolving flats) by the teeth of the card wire. This will be the case in cylinder wires as described in CN201258379Y and in the “camel type” cylinder wire as it is in conventional cylinder wires.
It is another drawback of these wires that the platform (in CN201258379Y) or the one hump (in the “camel type” card wire) is at a distinctly lower position than the tip of the tooth. Hence, the distance between the wire and a corresponding carding surface (e.g. on a short staple card between the platform or hump on the one hand, and the revolving tops on the other hand), will be significantly higher than the distance between the tip of the tooth and the corresponding carding surface. This fact can cause a lot of fibre rolling instead of fibre carding and hence the undesirable creation of fibre neps.